Paying constant attention to your BlackBerry could actually make you less productive, according to an occupational psychologist.

And recruitment agencies should offer their staff training in the best use of BlackBerrys and other mobile devices, adds the psychologist, Amir Khaki.

Khaki has conducted research into patterns of BlackBerry use which showed that those who did not use the device as frequently suffered less stress.

He told Recruiter that recruitment firms would benefit from giving their staff training on such devices. He said: “Even just short one-hour sessions would go a long way to stopping low levels of productivity and high levels of stress, because one of the main causes of stress is not knowing how to use the thing.”

Khaki added that using the technology in a “pervasive” way – which has given rise to the so-called ‘CrackBerry’ moniker - did not necessarily have the positive connotations many thought.

“People think that using them all the time is a sign of devotion to their work but at the same time, if you are using it when you are with your family, for example, other people may look upon it as a bit sad.

“Self-perception can be positive but outside perception can be negative.”

Khaki counselled recruiters to use their BlackBerrys at certain times and to deal with emails in “batches”, rather than responding to each one as it arrives, and only turning the device on at certain times during the day.

He also warned against so-called ‘BlackBerry thumb’ – repetitive strain injury to the digit caused by using the gadget too much.

Khaki’s research, produced in conjunction with the University of East London, took two groups of associates at law firms and monitored their BlackBerry use over three months, before analysing both quantitative and qualitative data.

He found that those paying constant attention to BlackBerrys were the least productive, and cited an example of one subject who was asked to complete a spreadsheet, a task which should have taken 20 minutes.

Due to his need to check his BlackBerry, the task took him more than an hour. “I agree that BlackBerrys are an essential tool but people should know how to use them and use them at appropriate times,” said Khaki.